A roller conveyor has been used for easily conveying articles in facilities such as factories or shipping storages. Such a roller conveyor includes a plurality of rollers, some of which are provided with an electric motor. Recently, a conveyor line formed by conveyors has got complex. In order to easily control such a complicated conveyor line, there is provided a conveyor consisting of a plurality of zones, into which a conveyor line is divided.
A roller conveyor consisting of a plurality of control zones is excellent in economic efficiency and less unproductiveness because articles are conveyed by rotation of motors with respect to each control zone instead of integrated operation of the entire roller conveyor. Additionally, it is possible to dispense with a complicated control system since the conveyor is divided into small ranges to be controlled.
Hence, such a roller conveyor having a plurality of control zones increases in frequency for activating and stopping the motors, rendering parts such as a gear, a belt, and a clasp that fixes a motor output shaft subject to wear.
For that reason, it is important to do maintenance of the roller conveyor, which is mostly left to one's discretion such as an experimental rule, determination from the timing of the introduction of those, determination by palpation, and determination by sound and smell. That is not easy.
A patent document 1 specified below discloses an equipment diagnosis method for easily determining a time for replacement of consumable members in a device such as an electric motor. The method disclosed in the patent document 1 is designed to determine a time for replacement on the basis of a difference between a current of a motor in no-load driving in a sound condition of a device and a current of the motor in no-load driving in operation.